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.TH RE_COMP 3C "Feb 26, 1997"
.SH NAME
re_comp, re_exec \- compile and execute regular expressions
.SH SYNOPSIS
.LP
.nf
#include <re_comp.h>

\fBchar *\fR\fBre_comp\fR(\fBconst char *\fR\fIstring\fR);
.fi

.LP
.nf
\fBint\fR \fBre_exec\fR(\fBconst char *\fR\fIstring\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBre_comp()\fR function converts a regular expression string (RE) into an
internal form suitable for pattern matching.  The \fBre_exec()\fR function
compares the string pointed to by the \fIstring\fR argument with the last
regular expression passed to \fBre_comp()\fR.
.sp
.LP
If \fBre_comp()\fR is called with a null pointer argument, the current regular
expression remains unchanged.
.sp
.LP
Strings passed to both \fBre_comp()\fR and \fBre_exec()\fR must be terminated
by a null byte, and may include \fBNEWLINE\fR characters.
.sp
.LP
The \fBre_comp()\fR and \fBre_exec()\fR functions support \fIsimple regular
expressions\fR, which are defined on the \fBregexp\fR(7) manual page. The
regular expressions of the form \fB\e{\fRm\fB\e}\fR, \fB\e{\fRm,\fB\e}\fR, or
\fB\e{\fRm,n\fB\e}\fR are not supported.
.SH RETURN VALUES
.sp
.LP
The \fBre_comp()\fR function returns a null pointer when the string pointed to
by the \fIstring\fR argument is successfully converted.  Otherwise, a pointer
to one of the following error message strings is returned:
.sp
.in +2
.nf
No previous regular expression
Regular expression too long
unmatched \e\|(
missing ]
too many \e\|(\|\e\|) pairs
unmatched \e\|)
.fi
.in -2

.sp
.LP
Upon successful completion, \fBre_exec()\fR returns \fB1\fR if \fIstring\fR
matches the last compiled regular expression.  Otherwise, \fBre_exec()\fR
returns \fB0\fR if \fIstring\fR fails to match the last compiled regular
expression, and \fB\(mi1\fR if the compiled regular expression is invalid
(indicating an internal error).
.SH ERRORS
.sp
.LP
No errors are defined.
.SH USAGE
.sp
.LP
For portability to implementations conforming to X/Open standards prior to SUS,
\fBregcomp\fR(3C) and \fBregexec\fR(3C) are preferred to these functions.  See
\fBstandards\fR(7).
.SH SEE ALSO
.sp
.LP
.BR grep (1),
.BR regcmp (1),
.BR regcmp (3C),
.BR regcomp (3C),
.BR regexec (3C),
.BR regexpr (3GEN),
.BR regexp (7),
.BR standards (7)
